This invention relates generally to filtering fluids, and particularly to filters which include self-cleaning elements.
Filters receive dirty fluid to be filtered in an external filter volume and pass the fluid through the filter. The cleaned fluid is received in an internal filter volume. The filter may be operated until the filter element becomes too dirty. Then, it is necessary to break the machine down, remove the filter element, and clean or replace the filter element. Thus, the amount of fluid that may be filtered is a function not only of the flow rate through the filter, but also of the downtime that results from filter replacement.
Greater time between filter element replacements may be possible with filters with self-cleaning elements. One way of providing a self-cleaning filter is to provide a backwash volume generally located in the external filter volume which cleans the dirty fluid side of the filter element. It is known to clean the filter element by spraying liquid on the dirty side of the filter element and by causing a backwash through the filter element.
While many important advances have been made in filter design, there is a continuing need for a filter which is capable of filtering fluids with a high concentration of solid material to be removed. Also there is a need for filters that can remove particles from a fluid of smaller particle size. There is also a continuing need for such filters which increase the mean time between filter element replacement. Obviously, the longer that the filter can operate without stoppage the greater the effective amount of fluid which may be filtered.